From patchwork Wed Jan 3 09:56:46 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 13509837 X-Patchwork-Delegate: kuba@kernel.org Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B12218E25; Wed, 3 Jan 2024 09:57:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.44]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4T4lVq5pjPz1wrCT; Wed, 3 Jan 2024 17:56:51 +0800 (CST) Received: from dggpemm500005.china.huawei.com (unknown [7.185.36.74]) by mail.maildlp.com (Postfix) with ESMTPS id 86A2B140258; Wed, 3 Jan 2024 17:57:21 +0800 (CST) Received: from localhost.localdomain (10.69.192.56) by dggpemm500005.china.huawei.com (7.185.36.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Wed, 3 Jan 2024 17:57:21 +0800 From: Yunsheng Lin To: , , CC: , , Yunsheng Lin , Alexander Duyck , Andrew Morton , Subject: [PATCH net-next 3/6] mm/page_alloc: use initial zero offset for page_frag_alloc_align() Date: Wed, 3 Jan 2024 17:56:46 +0800 Message-ID: <20240103095650.25769-4-linyunsheng@huawei.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20240103095650.25769-1-linyunsheng@huawei.com> References: <20240103095650.25769-1-linyunsheng@huawei.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500005.china.huawei.com (7.185.36.74) X-Patchwork-Delegate: kuba@kernel.org The next patch is above to use page_frag_alloc_align() to replace vhost_net_page_frag_refill(), the main difference between those two frag page implementations is whether we use a initial zero offset or not. It seems more nature to use a initial zero offset, as it may enable more correct cache prefetching and skb frag coalescing in the networking, so change it to use initial zero offset. Signed-off-by: Yunsheng Lin CC: Alexander Duyck --- mm/page_alloc.c | 30 ++++++++++++++---------------- 1 file changed, 14 insertions(+), 16 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1f0b36dd81b5..083e0c38fb62 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4720,7 +4720,7 @@ void *page_frag_alloc_align(struct page_frag_cache *nc, unsigned int fragsz, gfp_t gfp_mask, unsigned int align) { - unsigned int size = PAGE_SIZE; + unsigned int size; struct page *page; int offset; @@ -4732,10 +4732,6 @@ void *page_frag_alloc_align(struct page_frag_cache *nc, if (!page) return NULL; -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - /* if size can vary use size else just use PAGE_SIZE */ - size = nc->size; -#endif /* Even if we own the page, we do not use atomic_set(). * This would break get_page_unless_zero() users. */ @@ -4744,11 +4740,18 @@ void *page_frag_alloc_align(struct page_frag_cache *nc, /* reset page count bias and offset to start of new frag */ nc->pfmemalloc = page_is_pfmemalloc(page); nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1; - nc->offset = size; + nc->offset = 0; } - offset = nc->offset - fragsz; - if (unlikely(offset < 0)) { +#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) + /* if size can vary use size else just use PAGE_SIZE */ + size = nc->size; +#else + size = PAGE_SIZE; +#endif + + offset = ALIGN(nc->offset, align); + if (unlikely(offset + fragsz > size)) { page = virt_to_page(nc->va); if (!page_ref_sub_and_test(page, nc->pagecnt_bias)) @@ -4759,17 +4762,13 @@ void *page_frag_alloc_align(struct page_frag_cache *nc, goto refill; } -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - /* if size can vary use size else just use PAGE_SIZE */ - size = nc->size; -#endif /* OK, page count is 0, we can safely set it */ set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1); /* reset page count bias and offset to start of new frag */ nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1; - offset = size - fragsz; - if (unlikely(offset < 0)) { + offset = 0; + if (unlikely(fragsz > size)) { /* * The caller is trying to allocate a fragment * with fragsz > PAGE_SIZE but the cache isn't big @@ -4784,8 +4783,7 @@ void *page_frag_alloc_align(struct page_frag_cache *nc, } nc->pagecnt_bias--; - offset &= -align; - nc->offset = offset; + nc->offset = offset + fragsz; return nc->va + offset; }